Metallic particles are often present in materials such as spices, flour, sugar, chemicals and pharmaceutical ingredients. Before the materials may be further processed, the metallic particles must be removed. In many instances, magnetic forces or magnets may be used for removing the metallic particles from the material. The dry material, with the metallic particles removed, may then be further processed.
There have been a number of advances in metallic particle separating machines. For example, U.S. Pat. No. 4,457,838 to Carr discloses a self-cleaning magnetic separator for powered plastic and metal materials. The magnetic separator includes an inlet, a base plate and side plates. A plurality of vertically spaced staggered rows of laterally spaced pilot tubes are secured to the side plates to define a circuitous material falling path. An upright tube clearance plate is arranged intermediate the side plates and has a corresponding plurality of vertically spaced rows of laterally spaced apertures, oversized with respect to and loosely receiving the tubes defining clearance apertures. The clearance plate defines on one side an upright plastic feed chamber having an outlet in the base plate. An upright wiper plate is arranged between the clearance plate and one side plate having a corresponding series of apertures snugly receiving the tubes and defining with the adjacent side plate an upright metal feed chamber having an outlet. The elongated magnetic assembly is slidably mounted upon and intermittently reciprocal within each tube and is normally positioned within the plastic feed chamber. Falling particles of plastic cascade over the tubes within the plastic feed chamber for delivery through its outlet, however, the metal particles mixed in with the plastic particles adhere to the tubes. Upon intermittent retraction of the magnetic assemblies, the wiper plates strip the metal particles from the tubes and the metal particles fall within the metal feed chamber and through its outlet.
U.S. Pat. No. 4,867,869 to Barrett discloses a grate magnet apparatus including a frame having an opening adapted to have material pass therethrough. The apparatus includes a non-magnetic tube supported by the frame and extending across the opening, and an elongated magnetic member removably housed in the tube. Magnetic material is attracted to the tube when the magnetic member is housed in the tube. The magnetic material is released from the tube when the magnetic member is removed from the tube. The non-magnetic tubes and magnet members are connected both for joint movement to be withdrawn from the path of the flowing material and then for relative movement to release magnetic material from the non-magnetic tube.
U.S. Pat. No. 5,066,390 to Rhodes et al. discloses a magnetic separator with a reciprocal grate. The magnetic separator includes a plurality of elongated magnetic members that are parallel with one another. A first end plate is connected to adjacent terminal ends of the magnetic members to hold the magnetic members with the longitudinal axes generally defining a common plane. Non-magnetic sheathing members are disposed sheathing the entire longitudinal length of the magnetic members. A second end plate is connected to adjacent terminal ends of the non-magnetic members to provide longitudinal sheathing and unsheathing movement of the sheathing members with respect to the magnetic members for cleaning accumulated magnetic particles from the exterior surface of the non-magnetic members. The first and second end plates are adapted for reciprocating movement in the common plane, preferably in a direction generally perpendicular to the longitudinal axes of the magnetic members to reduce bridging and clogging of the material flow.
U.S. Pat. No. 5,188,239 to Stowe, U.S. Pat. No. 5,190,159 to Barker, U.S. Pat. No. 6,250,475 to Kwasniewicz et al., and U.S. Pat. No. 6,902,066 to Yang disclose other metallic particle separating machines that have magnetic tubes that are retracted for wiping or cleaning accumulated metallic particles from the tubes.
In spite of the above advances, there remains a need for a metallic particle separating machine that may be cleaned in a more efficient and efficacious manner. There also remains a need for a magnetic particle separating machine that may be continuously operated, and that does not have to be shut down or stopped in order to clean the internal components of the machine. There also remains a need for a metallic particle separating machine that efficiently collects magnetic particles for disposal.
These and other preferred embodiments of the present invention will be described in more detail below.